The invention relates to dock levelers used to bridge the gap between a loading dock and a vehicle (e.g. the bed of a truck or trailer) parked adjacent the loading dock, and more particularly to the maintenance, refurbishment, and upgrading of mechanical or hydraulic dock levelers.
Dock levelers are designed and built to provide years of reliable service with minimal periodic maintenance. The proper maintenance of the dock levelers depends on the type of dock leveler being used.
A mechanical dock leveler incorporates a large main spring or a multiple spring assembly to counterbalance the ramp or deck plate during movement between various positions. Mechanical dock levelers are typically operated manually using a pull chain and the weight of the operator as is commonly understood. Mechanical dock levelers will usually operate indefinitely with maintenance performed on the moving parts and with occasional replacement of the main spring or the multiple spring assembly. Replacing the springs is relatively expensive, but is cheaper than buying a whole new dock leveler.
A hydraulic dock leveler incorporates one or more hydraulic cylinders to move the ramp or deck plate between the various operating positions. Hydraulic dock levelers are less cumbersome to operate than mechanical dock levelers, but require more maintenance due to the use of the hydraulic cylinders, pumps and motors. The hydraulic fluid must be refilled and/or changed periodically, and the hydraulic cylinder must be replaced periodically. Replacing the hydraulic cylinders is relatively expensive, but is cheaper than buying a whole new dock leveler.
Mechanical and hydraulic dock levelers are the most common types of dock levelers in use today. But recent developments in the dock leveler art disclose a dock leveler using an inflatable member or bag to pivot the ramp (hereinafter referred to as an inflatable bag dock leveler). U.S. Pat. No. 5,802,650 discloses a dock leveler having a bag inflatable with low pressure air by an inflating device such as a fan or blower, and is hereby incorporated by reference in its entirety. Inflatable bag dock levelers have proven to be reliable alternatives to mechanical and hydraulic dock levelers, and the volume of new unit sales is rapidly increasing.
While the sale of new inflatable bag dock levelers is rapidly increasing, it is well-known that there are many more mechanical and hydraulic dock levelers already in operation around the world. It would be desirable to some people to upgrade from a mechanical or hydraulic dock leveler to a new, easy to operate, automatic, and environmentally-friendly inflatable bag dock leveler, but the expense of replacing an entire dock leveler is high, and therefore prohibitive. Even if the springs of mechanical dock leveler or the hydraulic cylinders, the pump, and the motor of a hydraulic dock leveler need to be replaced, it is usually less expensive to replace those parts than to buy a whole new dock leveler.
It would therefore be desirable to provide a cost effective method for upgrading a mechanical or hydraulic dock leveler to an inflatable dock leveler. The present invention provides a method for converting existing mechanical and hydraulic dock levelers to inflatable bag dock levelers, wherein the existing subframe, ramp, and extension lip are used. By converting existing dock levelers, instead of completely replacing them, the method and apparatus of the present invention provides a less expensive way to upgrade to an inflatable bag dock leveler.
More specifically, the invention provides a method of converting a non-inflatable dock leveler having a lifting mechanism to an inflatable bag dock leveler. The method includes removing the lifting mechanism from the non-inflatable dock leveler and coupling an inflatable lifting assembly to the dock leveler. Removing the lifting mechanism preferably includes removing the spring or the spring assembly of a mechanical dock leveler, or removing the hydraulic cylinder or cylinders, the pump, and the motor of a hydraulic dock leveler. The method preferably also includes connecting first and second support members to the non-inflatable dock leveler to support the inflatable lifting assembly.
In another aspect, the invention provides a dock leveler conversion kit. The conversion kit includes an inflatable lifting assembly and a first support member for supporting a first portion of the inflatable lifting assembly when the first support member and the inflatable lifting assembly are coupled to a dock leveler after the old lifting mechanism has been removed. Preferably, the conversion kit also includes a second support member for supporting a second portion of the inflatable lifting assembly.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.